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Polyphemus Moth

Antheraea polyphemus[3]

The polyphemus moth is one of the largest native silk moths, with a large eyespot on each hind wing; its plump, bright green caterpillar feeds on many shade trees but is rarely numerous enough to need control.[1][2]

Group
Insect
Order
Lepidoptera
Family
Saturniidae
US records
44 states
Sources
3 cited
Updated
2026-10-15
Large bright green polyphemus moth caterpillar with orange-red bumps on a twig
Large bright green polyphemus moth caterpillar with orange-red bumps on a twig. (c) Peter Waycik, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0
On this page
  1. Identification
  2. Look-alikes
  3. Where it lives
  4. Biology
  5. Damage and signs
  6. Health risk
  7. Control
  8. Common questions
  9. Sources

How to identify it

  • Full-grown caterpillars are bright to yellowish green, about 2 1/3 to 3 inches long, with orange to red bristly bumps and a yellow line running through the spiracles on each side.[1][2]
  • Adults have a 4- to 6-inch wingspan, are reddish brown, gray or yellow-brown, and have clear-centered eyespots, the hind-wing ones ringed in yellow, white and black.[1]
  • Mature caterpillars spin tough silk cocoons attached to twigs or leaves or found on the ground.[1][2]

Look-alikes

Look-alikeHow to tell them apart
Luna mothLuna moth cocoons are similar, but the polyphemus cocoon is single-layered, thicker and more oval.[1]

Where it lives

A widespread native silk moth; MU Extension reports caterpillars in Missouri yards from May to October.[1][2]

US map: public records from 44 states since 1990 (GBIF).

Biology and life cycle

MU Extension reports caterpillars from May to October with multiple generations a year in Missouri.[2]

Caterpillars pupate in silk cocoons on twigs, leaves or the ground.[2]

Damage and signs

  • Hosts include hickory, maple, oak, ash, walnut, sycamore, willow, elm, hawthorn, basswood and birch.[2]
  • A single caterpillar eats a lot of foliage, but numbers rarely reach levels that warrant control.[2]

Health risk

Neither source reports any risk to people or pets; silk moth caterpillars are not considered pests.[1][2]

Control

Prevention

No control is needed; silk moth caterpillars are usually not considered pests.[2]

Common questions

What is the huge green caterpillar on my oak?
Possibly a polyphemus moth caterpillar, which grows to about 3 inches.[1][2]
Will it hurt my tree?
Rarely; their numbers seldom reach damaging levels.[2]
Why does the moth have eyes on its wings?
Its large hind-wing eyespots give it the name, after the one-eyed giant Polyphemus.[1]

Sources

  1. University of Florida IFAS Extension (EDIS, Featured Creatures), “Polyphemus Moth, Antheraea polyphemus (EENY-531/IN945).” ask.ifas.ufl.edu/publication/IN945 (accessed 2026-10-15)
  2. University of Missouri Extension (Caterpillars in Your Yard and Garden, IPM1019), “Caterpillars in Your Yard and Garden, page 34: Polyphemus moth.” extension.missouri.edu/publications/ipm1019-34 (accessed 2026-10-15)
  3. iNaturalist, “Antheraea polyphemus taxon page (order and family).” www.inaturalist.org/taxa/47919 (accessed 2026-10-06)

Updated 2026-10-15. Built from sourced records. Spot an error? Tell us.